LS404

9/11

Figure 16 : Multiple Feedback 8-pole Bandpass Filter

Figure 17 : Six pole 355Hz Low-pass Filter (chebychev type)

This is a - pole Chebychev type with ±0.25dB ripple in the passband. A decoupling stage is used to avoid

the influence of the input impedance on the filter’s characteristics. The attenuation is about 55dB at 710Hz

and reaches 80dB at 1065Hz. the in band attenuation is limited in practise to the ±0.25dB ripple and does

not exceed 0.5dB at 0.9fc.

Figure 18 : Subsonic Filter (Gv = 0dB)

Figure 19 : High Cut filter (Gv = 0dB)

IN

C1

0.1 F

m

R1

C2

R4

Vcc

R2

R3

22k

W

22k

W

1

2

3

4

R5

C3

C4

0.1 F

m

¼

LS404

¼

LS404

¼

LS404

¼

LS404

R6

R7

C5

C6

R8

R9

R10

C7

220 F

m

C8

C9

R11

7

11

5

6

8

9

10

R12

R13

C10

C11

R14

14

13

12

Out

C12

0.1 F

m

C13

0.22 F

m

56k

Ω

0.47 F

µ

10k

Ω

10k

Ω

86.1nF

161nF

10k

Ω

10k

Ω

220nF

16.3nF

10k

Ω

10k

Ω

60nF

3.54nF

10k

Ω

C

C

22k

Ω

Vout

Fc (Hz)

15

22

30

55

100

C ( F)

0.68

0.47

0.33

0.22

0.10

µ

C2

10k

Ω

Vin

C1

Vout

10k

Ω

3

2

1

Fc (Hz)

3

5

10

15

C1 (nF)

3.9

2.2

1.2

0.68

C2 (nF)

6.8

4.7

2.2

1.5